For example, JP2015-110417A discloses a drive assistance device that increases a degree of assistance of a driving operation (e.g., a degree of assistance when parking) when a driving skill of a vehicle driver is insufficient against a required level corresponding to an environmental difficulty based on an outside environment.
However, while increasing the degree of assistance enhances the driver's driving skill, if drive assistance is provided to a driver with a high driving skill, the driving becomes boring for the driver and the driver's performance may gradually degrade.